Intermediate Events

Intermediate events can throw or catch events with a specified trigger type after a process instance has started.

Intermediate events can be used as follows:

  • Intermediate events can be used "in-flow", that is, between two other activities.
  • Most catch-type intermediate events can be attached to a task boundary to catch a triggered event only while that task is in-progress.
  • You can define an event handler by starting a flow with an intermediate event. See Event Handlers (trigger type support is destination specific).

You can use the following types of intermediate events:

Note: There are some restrictions on the placement of intermediate events. For example:
  • Intermediate events of type Link cannot be placed on the boundary of a task.
  • Intermediate events of type Cancel cannot be placed in sequence flow.

Restrictions are placed upon the ways that you can use events; these are enforced via problem markers.

  • Incoming Request Event -  Event that is triggered via the public REST API.
  • Catch Timer - The event is triggered at a specific date/time or at a regular interval (time cycle). When placed on the boundary of a task, a timer event defines a deadline for the task. In the Properties view for the event, Use as activity deadline is preselected. If more than one timer event is attached to a task, only one of them can be selected as the timer deadline. If there is a cancelling timer, then it must be selected as the deadline.

    There are two options you can select from to decide how the task is treated if the event times out (Withdraw Task on Timeout and Continue Task on Timeout).

  • Throw/Catch Link -  Indicates a connection from one or more throw link intermediate events to a catch link intermediate event in the same parent process/parent embedded sub-process. This can be thought of as a "go to" or "off page connector" that you can use to break up a process for better legibility.
  • Throw/Catch Signal - Broadcasts or catches a signal. A throw signal event is assigned a default signal name (signaln). You can use a catch signal attached to a user task boundary to resend data to the outstanding work item for that task
  • Throw Error -  Attached to a task boundary to end a sub-process with an error.
  • Catch Error -  Attached to a task boundary to catch an application error that occurs during the processing of that task. Either catches the specified error, or catches any error if no specific error is specified.
  • Catch Cancel - Catches a sub-process cancel.
  • Throw/Catch Compensation - Used to process compensating activities for previously executed tasks:
    • If located in a sequence flow of the process, this event throws a call for compensation.
    • If attached to the boundary of an activity, this event catches a named compensation call.